Bulimia, the binge-eating syndrome, is a widespread and perhaps increasingly prevalent public health problem. The full-blown disorder may be accompanied by severe psychologic and physiologic sequelae. Much remains to be learned about the nature and treatment of this disorder. Thus three related studies examining aspects of the treatment and psychopathology of bulimia are proposed. Uncontrolled studies suggest that a cognitive behavioral treatment applied individually or in a group format is a promising approach to the treatment of bulimia, but no controlled treatment studies have appeared to date. In Study 1, 60 bulimic women will be allocated at random to three treatment conditions: cognitive behavioral therapy, with or without attention to vomiting, and a control condition. Treatment will be carried out in a group format over a one-year period and a multilevel assessment will include measures of eating behavior, binging and vomiting, body weight and electrolytes, and psychologic indices. Selected follow-up measures will be obtained six months and one year after the end of the initial treatment phase. An examination will be made of baseline variables that might predict treatment outcome. In Study 2, a comparison sample of women with normal eating behavior will allow a comparison of normal and bulimic eating styles and an estimate of the degree of normalization of bulimic eating patterns posttreatment. In Study 3, the first degree relatives of both bulimic and normal participants will be examine for the presence of eating disorders, such as bulimia, anorexia nervosa, and obesity, as well as primary affective disorders, alcoholism, and substance abuse. This will allow for an estimation of the relative prevalence of these disorders in relatives of bulimic and nonbulimic women and help to determine the relationship between bulimia and other psychiatric disorders.